Slidable door safety lock

ABSTRACT

A sliding door security lock of telescoping members limited in movement in a contracted direction, one end being attached to the frame of the sliding door itself and the other end being attached to the doorjamb or a second door in the doorjamb. Both attachments are releasable, one by retracting one member from one member when the door is closed and the other by angularly moving the other member when the one member is retracted therefrom. The one member is latched by a pivoted coaxial keeper in its telescoping position and the latch is held closed by the other member when the door is open.

United States Patent Francis B. Mueller 4917 Chase Ave., Downers Grove,111. 60515 Oct. 30, 1969 Sept. 28, 1971 [72] inventor 2| App]. No. [22]Filed [45] Patented [54] SLIDABLE DOOR SAFETY LOCK 262, 305, 338, 278',70/90, 94, 95; 49/449, 450; 287/58 CT; 248/354 R; 21 1/105.3, 123

[56] References Cited UNITED STATES PATENTS 534,923 2/1895 Shout 292/2621 ,601,524 9/ 1926 Gibbons 292/305 Primary Examiner- Robert L. WolfeAttorney-Harbaugh and Thomas ABSTRACT: A sliding door security lock oftelescoping members limited in movement in a contracted direction, oneend being attached to the frame of the sliding door itself and the otherend being attached to the doorjamb or a second door in the doorjamb.Both attachments are releasable, one by retracting one member from onemember when the door is closed and the other by angularly moving theother member when the one member is retracted therefrom. The one memberis latched by a pivoted coaxial keeper in its telescoping position andthe latch is held closed by the other member when the door is open.

PATENIED was Ian SHEU 1 [1F 3 FEB! FRANCIS B. MUELLER PATENTED SEP281971 SHEET 3 OF 3 FRANCIS B. MUELLER You,

SLIDABILE DOOR SAFETY LOCM BACKGROUND OF THE INVENTION Sliding closuresare used in modern access openings of which slidable glass panel doorsare an example. Other examples include specially designed fire doors,windows, room cutoff panels, and related enclosures. Generally, theglass is supported in frames that are mounted for movement in channelmembers of a doorjamb. Normally the usual key-operated locks are usedwith these types of structures and it is the practice where plate glassor Thermopane glass panels of relatively large areas are used in thedoors, the locks are located in narrow frame members rather than theglass itself. Experience has taught that the locks employed can beforced by the pry of a crowbar or wedge and can be disengaged by forcingsteel chisels through the outer frames at the position of the lock.

Several forms of safety locks for sliding doors have been developed aswith fingers engageable with selected notches in the top edges of thepanels in their closed position which is secured by an ordinarykey-operated cylinder lock. However, the lock once set locks the door ina fixed position and in many instances have vulnerable elements exposed.This type of locking a door in particular positions also has thedisadvantage of being somewhat complicated and depends on the use of akey each time the door is opened a little farther and its location isgenerally along the top or bottom of the framework for the slidingpanels. No provision is made for a readily available, partial opening ofthe panels under locked conditions.

Various forms of disengageable safety locks are available for hingeddoors such as chains, bars, etc. in difierent arrangements. It is commonto use a plain piece of wood or pipe to fit between the frame of awindow and one of the movable sashes. In one embodiment a telescopingmember is used which can be locked to a desired length by a setscrew.Such inserted members can be pried or lifted loose by fiat toolsinserted through joints and cracks in the frames and are not foolproof.In brief no satisfactory sliding-door lock having foolproofcharacteristics is available. The instant invention overcomes these andrelated problems.

SUMMARY OF THE INVENTION The instant invention concerns a strong safetylock for sliding structures that can be used in any attitude, isfoolproof, provides variable partial opening of the structure forventilation purposes, cannot be opened or unlocked in its partially openposition and requires that the structure be fully closed before the lockcan be opened. The lock of this invention is constructed of readilyfabricated, simple, yet rugged parts and is not unsightly.

The safety lock of this invention is easily installed, has theappearance of a handle or guard rail on the structure door and in factone of the parts, when the lock is not in use can function as a handlefor a sliding door, while the other part can be detached, leaving theglass pane of the door free of obstructions. The safety lock of thisinvention cannot be half locked or placed in a position where it appearsto be locked when in fact it is not locked. If the detachable member isheld in a position across the panel of glass, the door is looked, acondition that can be determined even in a dimly lighted room or fromlight coming through the panel from the outside only. Furthermore, thelock of this invention can without modification be used on a singlesliding door or a pair of doors which operate or overlap within the sameopening.

More particularly the safety lock of this invention comprises a rodmember with a hook at one end and a tubular section at the other end. Akeeper is provided and adapted to be affixed to a stationary wall or theframe of a second door which closes in the other direction. The keeperhas an eye adapted to be engaged by the hook end of the rod. A swingbolt assembly is provided with a bracket for attachment to the door sideframe or to a stationary frame, as desired. The bracket has a stationaryslotted portion and a beveled abutment. The bolt is provided with a pinthat engages the slot allowing the swing bolt to reciprocatelongitudinally in a plane parallel to the plane of movement of thesliding door or doors and swings in an are away from the door and out ofaxial alignment with the rod member. The extended end of the bolt isadapted to be telescopingly engaged within the tubular section of therod, when the latter is axially aligned therewith within the limits ofthe movement of the pin in the slot. The bolt carries a latch memberwithin its extended end that is pivotally mounted on an axissubstantially perpendicular to the plane of movement of the door andalso perpendicular to the axis of the pin on the bolt. The opposite orpivotable end of the latch member is adapted to engage the abutment ofthe bracket member in the locked position and be pivoted upwardly to anunlocked position where it overrides the abutment and allows the bolt tomove out of telescoping relationship with the tubular section of the rodmember. section of the The telescoping relationship of the rod and boltallows limited opening of the door, for ventilation, and at the sametime encompasses the latch member so that it cannot be pivoted above theabutment. To secure the lock it is only necessary to close the door orpanel completely, insert the hook end of the rod into the keeper, swingthe bolt assembly into axial alignment with the tubular section of therod, raise the latch, slide the bolt away from the rod to the limits ofthe pin in the slotted bracket and then mate the bolt with the tubularsection and slide it therein. In this last step the latch automaticallyfalls into place and engages against the abutment so that the boltcannot disengage the tubular section. The door and frame are now tiedtogether within the overlapping limits of the tubular section and thebolt. Reversal of these steps unlocks the lock.

The safety lock of this invention can be used for any type of slidingpanel structure such as sliding doors, sliding windows, double-hungwindows and single-hung windows. When using the device of this inventionfor a window lock, the mounting would be along the jamb. Otherembodiments of the invention will become apparent as the descriptionproceeds.

DESCRIPTION OF THE DRAWINGS An illustrative nonlimiting embodiment ofthis invention is shown in the drawings wherein:

FIG. l is a plan view of a wall showing sliding glass door panels withthe safety lock of this invention in the locked position;

FIG. 2 is a fragmentary partial cross-sectional top view taken along thelines 22 of FIG. ll of the safety lock of this invention in the lockedposition;

FIG. 3 is a fragmentary partial cross-sectional side view of the lock inthe position shown in FIG. 2;

FIG. 4 is a fragmentary view like FIG. 2 showing the lock in the lockedposition and one or both of the doors in a partially opened position;

FIG. 5 is an exploded perspective view of the swing bolt assembly;

FIG. 6 is a fragmentary perspective view of the safety lock of thisinvention in the locked position and the door or doors in closedposition as shown in FIGS. 1, 2 and 3;

FIG. 7 is a fragmentary perspective view of the safety lock in theunlocked position with the swing bolt assembly unlatched and extended tofree the rod member.

THE PREFERRED EMBODIMENT Referring to FIG. 1 there is shown arepresentative wall or frame with a pair of glass panel doors 112 and 14illustrating sliding structures, one or both of which are horizontallyslida ble within a suitable framework or jamb 116 having tracks (notshown) along which the horizontal frame members 18 and 20 of the doorsfor example, are guided. The panel 12 has a pair of upright framemembers 22 and 24! forming a unitary structure, and similarly the panelM has a pair of upright frame members 26, one of which would be behindthe upright M in the indicated position of the panels. Attached betweenthe frame member 24 of the panel 12 and the frame member 26 of the panel14 is the safety lock 30 of this invention, in this instance shown inits locked position with the parts in their extended position and withthe panels completely closed.

Referring to FIGS. 2 and 3 an example of the detailed structure is shownwherein the safety lock 30 consists of the keeper member 32 having thebaseplate 34 with the corner flange 36 fitted to and around the cornerof the frame member 26 of the panel 14 here indicated to be a Thermopaneglass door. Any securing means such as the screws 38 can be used tofasten the keeper member 32 to the frame and suitable holes (notindicated) would be provided in the baseplate to accommodate the screws.

The keeper member 32 has the eyelet or eye member 40 defining theopening 42 which is generally frustoconical in configuration beinglarger on the inside periphery 44 than the outer periphery 46 so as toreceive and retain the hook member 48 of the rod member 50.

The rod member 50 is generally tubular in configuration having aninternal bore 52 extending part or all of its length with the hook base54 forming an end closure. The hook 48 is integral with the base 54 andcan be welded within the rod 50 or attached by means of the rivet 56extending through suita ble aligned bores in these members. The hook 48is adapted to engage the opening 42 with the narrow curved portion 58 inthe inside of the hook providing limited plan within the keeper, yetallowing easy removal when the rod 50 is swung in the direction of thearrow 60. This action is facilitated by the frustoconical shape of theopening 42. The hook 48 may be so dimensioned that the screw 38 cannotbe removed when the hook is in place.

The other end of the safety lock 30 has the bracket member 62 similar tothe baseplate 34, encompassing the corner of the frame member 24 of theThermopane glass panel 12, and held thereto by means of the screws 64and 66 in a manner similar to the keeper 32. The bracket 62 has thehorizontally extending cleat or flange 68 provided with the elongatedslot 70. The slot extends through both sides of the cleat 68 and isoriented in the general direction of the movable structure.

The cleat 68 has the lock member or abutment 72 extending axially of theslot 70 and provided with the upwardly beveled end 74 extendingtransverse the axis of the slot 70 and sloping upwardly toward thekeeper 32 when these parts are mounted on the respective frame members.The details of the cleat 68 are shown in FIG. 5. The lock member 72 isseen to provide a fixed wall or abutment under the plane of the cleat 68for purposes to be described.

The bracket 62 serves as a permanent sliding hinge mount for the swingbolt assembly 76 comprising an elongated rod 77 with one end 78 adaptedto be telescopingly received in the bore 52 of the rod 50 with aclose-fit clearance as indicated at the space 80 and having a chamferededge 82 to facilitate its insertion therein. The swing bolt 76 is cutoutor offset to form the elongated side channel or notch 84 (better shownin FIG. defined by the transverse or radial wall 86 at the outer end,the longitudinal wall 88 which extends axially of the bolt and thebeveled end wall 90 (see FIG. 8) at the inner end nearest the bracket62.

The telescoping end 78 of the swing bolt or rod 77 may be generallycylindrical to match the shape of the bore 52 and the other end 94 isgenerally reduced in cross section and flattened on all four surfaces,having an offset beveled edge 92 on the bottom and intermediate thewalls 86 and 94, and the chamfered edge 96 at the juncture of thesesurfaces. Thus, the flattened or squared end 94 has the flat bottomsurface 98 which rests upon the top flat surface 100 of the cleat 68,and also upon the lock or extension member 72. The flat end 94 carriesthe pin 102 near its terminus. The pin 102 extends through the slot 70and is engaged therein by the head 104. The head 104 has a diameterlarger than the slot 70 and engages against the flat undersurface 106 ofthe lock member 72 in a sliding relationship while maintaining thesurface 98 against the surface 100, in a bearing relationship.

The offset 84 provides a recessed housing for the latch member 1 10.This latch has the cross bore 1 12 at one end with an enlargedcounterbore 114 concentric therewith to receive the enlarged head 116(FIG. 2) of the pivot pin 118 that extends through the bore 120 throughthe rod 77 at the wall 88.

The pivoted end of the latch member 110 is rounded as at 122 orotherwise spaced from the radial wall 86 of the offset 84 so as to bepivotally mounted on the pivot pin 118 and has a beveled end 124 thatmatches with and engages upon the oppositely beveled surfaces 74 and ofthe cleat 68 and the swing bolt 76, in a manner to be described.

Referring first to FIGS. 2 and 3, the safety lock of this invention isshown in the locked position wherein the rod 77 extends a short distanceinto the tubular portion 52 of the rod member 50 when moved to thelimits of the slot 70 in which position the pin 102 is against the endof the slot as indicated at the contact line 126 in FIG. 3. The abuttingsurface 90 of the rod 77 has been moved into planar alignment with theabutting surface 74 of the lock member 72, extending thereunder from thecleat 68. This allows the latch member to be pivoted downwardly or fallby gravity into the locked position shown with its beveled end 124engaged upon the coplanar surfaces 74 and 90. The sliding structure,e.g. the door 14, is in the completely closed position with the frame 26against the jamb 16. This relationship of the parts of the lock is alsoshown in FIG. 6.

The door 14 is however free to be opened slightly for ventilation, ifdesired, because of the telescoping relation of the rods 50 and 77. Theextent of such opening is a matter of choice and would normally beinsufficient to allow the entry of an intruder, e.g., 4-5 inches. Thesliding of the door 14 to the partially opened but still locked positioncauses the parts to assume the relationship shown in FIG. 4 where thespace 128 represents the relative amount of such opening. It is to beobserved that the tubular portion 52 of the rod 50 has passed over thelatch member 110 and rod 77, completely encompassing and hiding same andmaking it impossible to unlatch. The extend of this partial opening ofthe door is limited by the abutment of the edge 130 of the rod 50against the front surface 63 of the L-shaped flange 62 or the sideflange 63 as indicated in FIG. 4. The extent of this sliding, but lockedrelationship of the door 14, can be represented by the distance betweenthe lines A-B which will of course be equal to the space 128. Thisopening is independent of the length of the slot 70.

It will be also observed that in this position of the lock the rod 77 isstill in its right-hand or extended position in relation to the slot 70and that the pin 102 is in contact with the slot at 126. The beveledsurface 92 of the rod 77 is also spaced from the beveled surface 74 ofthe cleat 68 as shown in FIG. 4. This distance between the beveledsurface 92 and the beveled surface 74 when the assembly is in theposition shown in FIGS. 1-4 and 6 is also about equal to the length ofthe slot 70 and preferably these distances are exactly equal.

Accordingly, in order to unlock the latch member 110, the door 14 mustbe moved to the right, closing the space 126 and bringing the assemblyto the position shown in FIGS. 1, 2, 3 or 6. The door is closed and isstill. securely locked, and in this condition the latch 110 cannot bereached from the outside. The slightest opening of the door 14 moves thetubular member 50 onto the latch member 110 so that it cannot bepivoted. However, from theinside of the door, the latch 110 can belifted by slight finger? pressure indicated by the arrow 132 (FIG. 6) orby grasping the rod 77 and thrusting it to the left e.g., in thedirection of the arrow 134 or both of these forces simultaneously. Inthe case of a lateral thrust of the rod 77 toward the bracket, thebeveled end surface 124 of the latch member 110 cams upwardly on thebeveled surface 74, and the latchassumes the open position shown in FIG.7 with the pin 102 against the left-hand end 136 of the slot 70 and thebeveled surface 92 of the rod 77 against the beveled surface 74 on theend of the cleat 68. The latch member 110 than rides up to the positionshown as it pivots on the pin 118. This frees the end portion 78 fromthe tubular rod 50 and the latch assembly 76 can be horizontally pivotedin the direction of the arrow 138 or the rod 50 pivoted in the samedirection on the hook 48 to free those members from each other andunlock the door.

It is apparent from this description that the safety lock described canbe modified in a number of ways and still retain the locking anunlocking features that have been explained. The pair of bracket memberscan be in any attitude to accomplish their functions, and adapted to beindividually attached in spaced relationship along a longitudinal axisto a pair of structures movable along that axis in relation to eachother. Thus, both doors l2 and M can be slidable or one of them can bestationary. The lock can be used between the upper and lower sashes ofdouble-hung windows or between any relatively movable structures. Theslot 70 can extend horizontally through an upstanding flange rather thanvertically through a horizontal flange as illustrated.

The various interlocking and abutting beveled surfaces such as 74, 90,592 and 124 can be at any desired angle as long as the latch 11110 isreleasable by pivoting upwardly and in the locked position forms a swingbolt assembly which will telescope in the manner shown in FIG. 4. Thecross-sectional configuration of the parts such as the swing bolt can bechanged from that shown without changing the cooperative functioning ofthe parts.

The surfaces 9t) and 7d do not have to be coplanar when the bolt is inthe position shown in FIGS. 2 and 3 and 6, since the end surface 124 ofthe latch member 1110 can be notched or otherwise contoured to mate withany offset in the surfaces 90 and 7d. The surface 90 can be omitted sothat a space is provided at the juncture of the surface 124 and thisabutment, although the structures shown are preferred for smoothoperation of the parts and freedom from hang up etc.

Likewise the surface 92 on the rod 77 can be omitted although itsrelationship with the back part of the surface 7 strengthens the lockand spreads the forces applied to the bracket 62. That part of thesurface 74 which registers with the surface 92 does not have to becoplanar with the part of the surface 7% which registers with thebeveled end 124 of the latch member 1110 and can be offset either sideof the coplanar relationship shown.

The location of the various screws holding the bracket and keepermembers can be such that they are attachable only when the spring boltassembly is unlocked and swung 90 away from the bracket and the hookmember as is detached. This eliminates the possibility of disassembly ofthe lock in its locked position. Likewise, the latch member lllltl canbe closely contoured to appear as a part of the rod 77 so that it is notimmediately apparent to an outsider that it is a seperable and pivotalmember.

The lock of this invention is fabricated of steel or other suitablemetal having sufficient strength to withstand hard usage and resistbreaking or bending under the lever action of a crowbar or other burglartools. Advantages of the lock of this invention are its simplicity ofoperation, the concealed and absolutely secure position of the latch inpartially opened position and the adaptability to structures in anyattitude without change in the structure of the lock.

The security lock can be applied to any slidable closure and a secondstructure having a fixed spaced relationship in their closed positionwhether or not the second structure is stationary or also slidable. Thepair of elongated members comprising the rod 50 and swing bolt assembly76 are adapted to bridge the space between the slidable closure and thesecond structure with their inner ends in telescoping relationship. Anymeans can be used to separately support the extended ends of theelongated members to the parts to be locked, preferably one support is apin-slot arrangement and the other a detachable hook, the former beingin permanent sliding orientation with the axis of the telescopingarrangement and the latter being detachable only when the one elongatedmember is moved out of telescoping alignment. The invention provides inthe swing bolt assembly a means to lock one of the elongated members atits support in a first retracted position toward the other elongatedmember whereby the telescoping relationship is retained yet limited andstill protective opening of the closure is provided. The locking meansis adapted to be releasable whereby the one elongated member can beextended to allow clearance disengagement of the telescopingrelationship in the closed position of the closure and thus unlock thedevice. in all other positions of the locking means the inner end of oneof the telescoping members overlaps the latch sufficiently so that itcannot be released. The distal end of the latch can automatically camupwardly into the released position in one embodiment.

What is claimed is:

ll. A security lock for a slidable closure having a fixed spacedrelationship with a second structure in its close position comprising:

a pair of elongated members adapted to bridge the space between saidslidable closure and said second structure with their inner ends intelescoping relationship,

means to separately support the extended ends of said elongated rnembersto said slidable closure and to said second structure whereby saidclosure and said second structure are movable in relation to each otherin a predetermined telescoping distance,

means to lock one of said elongated members at said support means in afirst retracted position toward the other elongated member whereby saidelongated members are retained in said telescoping relationship to allowlimited opening between said closure and said structure,

said locking means including a latch member so positioned as to beoverlapped and immobilized by the inner end of the other of saidelongated members in said retracted position and being releasable in theextended position of said one elongated member whereby said oneelongated member is movable to an extended position away from the otherelongated member to allow clearance disengagement of said telescopingrelationship in the closed position of said slidable closure wherebysaid slidable closure is unlocked.

2. A security lock in accordance with claim 1 in which said supportmeans and the extended end of said one elongated member are connected byslidably interengaging elements allowing axial movement of said oneelongated member in relation to the other elongated member to and fromsaid retracted and extended position,

said latch member being pivotally :mounted on said one elongated memberat a point outside the terminus of said telescoping relationship of saidelongated members in their extended axial positions,

the distal end of said latch member being disposed toward saidaforementioned support means, and

an abutment of said support means adapted to engage the distal end ofsaid latch member and retain said one elongated member in the retractedposition.

3. A security lock in accordance with claim 2 in which: said slidablyinterengaging elements comprise pin and slot elements of suchorientation and dimension as to afford relative movement between saidretracted and extended positions.

Al. A security lock in accordance with claim 3 in which:

said support means and the extended end of said one elongated memberengage one upon the other by means of opposing planar bearing surfacesand are connected by said slidably interengaging elements so that saidone elongated member is movable to and from said retracted and extendedpositions and is adapted to be pivoted on said planar bearing surfacesout of telescoping engagement with said other elongated element in theextended position of said one elongated member and the release positionof said latch member.

5. A security lock in accordance with claim t in which:

said abutment on said support means is provided with a beveled surfacefacing said latch member,

one of said slidably interengaging elements comprises a slot in saidabutment having its longer axis aligned with the axis of saidtelescoping relationship of said elongated members,

the other of said slidably interengaging elements comprises a pindepending from said extended end of said one elongated member andengaged in said slot against axial displacement,

an elongated recess is provided in the side of the extended end of saidone elongated member with a beveled wall at the end of said recessnearest said pin,

said latch member is pivotally mounted at one end within said recesswith its distal end supported upon said beveled wall,

said other elongated member has a tubular inner end and the inner end ofsaid one elongated member telescopes therein, I

the space between the inner end of said slot and said abutment beingsubstantially the same as the space between said pin and the beveledwall of said recess, whereby with said one elongated member in theretracted position said latch member occupies said recess and saidtubular elongated member telescopes thereover to allow limited openingof said slidable closure and also with the inner ends of said elongatedmembers at the extended limit of their telescoping relationship, uponmovement of said one elongated member to its extended position withinsaid slot the distal end of said latch member automatically ridesupwardly on said beveled surface of said abutment to allow the inner endthereof to clear its telescoping relationship with the tubular inner endof said other elongated member and unlock said slidable closure.

6. A security lock in accordance with claim in which:

the extended end of said one elongated member is provided with an ofisetwall adapted to engage the abutment of said support means in theextended position of said pin and slot.

7. A security lock in accordance with claim 5 in which:

the length of the telescoping relationship of said elongated members inthe retracted position of said one elongated member is sufficientlygreater than the length of said latch member to allow same to pivot tothe unlocked position.

8. A security lock in accordance with claim 5 in which:

the means to support said other elongated member comprises a combinationhook-and-eye attachment at the extended end thereof, said hook and eyebeing disengageable only with the inner end of said elongated membermoved away from said telescopic alignment.

9. A security lock for a sliding closure comprising first and secondelongated members in telescoping relation overlapping a predetennineddistance for supporting themselves in alignment,

means for controlling said telescoping relation including slidablyinterengaged pin and slot elements in which said slot is of a length andorientation to afford relative movement of the pin element approximatelysaid predetermined distance,

bracket means for securing one of said elements to a support that isstationary with respect to said sliding closure and limiting movement ofthe other one of said elements to the length of the slot,

said first elongated member carrying the other one of said elements fordisassociation of said telescoping relationship by relative movement ofsaid members in one direction,

one of said elements carrying a shoulder,

latch means movably mounted with respect to one of said elongatedmembers to clear said shoulder when movement in said one direction ismade, said latch means engaging said shoulder at other times to holdsaid members a ainst said disassociation movement, loc mg means carriedby one of said members engaging said latch means and securing it in itsshoulder-engaging position while said members are moved relative to eachother in a direction opposite to said one direction,

stop means carried by one of said members for limiting the distance offurther telescoping movement between them in said other direction, and

means securing the second member to the sliding closure.

10. The combination called for in claim 9 in which said securing meansis releasable and comprises interlocking elements, one having an openingand the other having an angular member received through said opening andthe inner portion of said angular member being disposed in interferenceengagement with said other interlocking element as oriented bytelescopic movement of said second member, said angular member beingmoved from said interference engagement when said telescopingrelationship is disassociated and said telescoping members are movedfrom axial alignment.

11. The combination called for in claim 9 in which said securing meanscomprises hook-and-eye elements and the terminal end of said hook isdisposed at an angle to the axis of the telescoping relation.

1. A security lock for a slidable closure having a fixed spaced relationship with a second structure in its close position comprising: a pair of elongated members adapted to bridge the space between said slidable closure and said second structure with their inner ends in telescoping relationship, means to separately support the extended ends of said elongated members to said slidable closure and to said second structure whereby said closure and said second structure are movable in relation to each other in a predetermined telescoping distance, means to lock one of said elongated members at said support means in a first retracted position toward the other elongated member whereby said elongated members are retained in said telescoping relationship to allow limited opening between said closure and said structure, said locking means including a latch member so positioned as to be overlapped and immobilized by the inner end of the other of said elongated members in said retracted position and being releasable in the extended position of said one elongated member whereby said one elongated member is movable to an extended position away from the other elongated member to allow clearance disengagement of said telescoping relationship in the closed position of said slidable closure whereby said slidable closure is unlocked.
 2. A security lock in accordance with claim 1 in which said support means and the extended end of said one elongated member are connected by slidably interengaging elements allowing axial movement of said one elongated member in relation to the other elongated member to and from said retracted and extended position, said latch member being pivotally mounted on said one elongated member at a point outside the terminus of said telescoping relationship of said elongated members in their extended axial positions, the distal end of said latch member being disposed toward said aforementioned support means, and an abutment of said support means adapted to engage the distal end of said latch member and retain said one elongated member in the retracted position.
 3. A security lock in accordance with claim 2 in which: said slidably interengaging elements comprise pin and slot elements of such orientation and dimension as to afford relative movement between said retracted and extended positions.
 4. A security lock in accordance with claim 3 in which: said support means and the extended end of said one elongated member engage one upon the other by means of opposing planar bearing surfaces and are connected by said slidably interengaging elements so that said one elongated member is movable to and from said retracted and extended positions and is adapted to be pivoted on said planar bearing surfaces out of telescoping engagement with said other elongated element in the extended position of said one elongated member and the release position of said latch member.
 5. A security lock in accordance with claim 4 in which: said abutment on said support means is provided with a beveled surface facing said latch member, one of said slidably interengaging elements comprises a slot in said abutment having its longer axis aligned with the axis of said telescoping relationship of said elongated members, the other of said slidably interengaging elements comprises a pin depending from said extended end of said one elongated member and engaged in said slot against axial displacement, an elongated recess is provided in the side of the extended end of said one elongated member with a beveled wall at the end of said recess nearest said pin, said latch member is pivotally mounted at one end within said recess with its distal end supported upon said beveled wall, said other elongated member has a tubular inner end and the inner end of said one elongated member telescopes therein, the space between the inner end of said slot and said abutment being substantially the same as the space between said pin and the beveled wall of said recess, whereby with said one elongated member in the retracted position said latch member occupies said recess and said tubular elongated member telescopes thereover to allow limited opening of said slidable closure and also with the inner ends of said elongated members at the extended limit of their telescoping relationship, upon movement of said one elongated member to its extended position within said slot the distal end of said latch member automatically rides upwardly on said beveled surface of said abutment to allow the inner end thereof to clear its telescoping relationship with the tubular inner end of said other elongated member and unlock said slidable closure.
 6. A security lock in accordance with claim 5 in which: the extended end of said one elongated member is provided with an offset wall adapted to engage the abutment of said support means in the extended position of said pin and slot.
 7. A security lock in accordance with claim 5 in which: the length of the telescoping relationship of said elongated members in the retracTed position of said one elongated member is sufficiently greater than the length of said latch member to allow same to pivot to the unlocked position.
 8. A security lock in accordance with claim 5 in which: the means to support said other elongated member comprises a combination hook-and-eye attachment at the extended end thereof, said hook and eye being disengageable only with the inner end of said elongated member moved away from said telescopic alignment.
 9. A security lock for a sliding closure comprising first and second elongated members in telescoping relation overlapping a predetermined distance for supporting themselves in alignment, means for controlling said telescoping relation including slidably interengaged pin and slot elements in which said slot is of a length and orientation to afford relative movement of the pin element approximately said predetermined distance, bracket means for securing one of said elements to a support that is stationary with respect to said sliding closure and limiting movement of the other one of said elements to the length of the slot, said first elongated member carrying the other one of said elements for disassociation of said telescoping relationship by relative movement of said members in one direction, one of said elements carrying a shoulder, latch means movably mounted with respect to one of said elongated members to clear said shoulder when movement in said one direction is made, said latch means engaging said shoulder at other times to hold said members against said disassociation movement, locking means carried by one of said members engaging said latch means and securing it in its shoulder-engaging position while said members are moved relative to each other in a direction opposite to said one direction, stop means carried by one of said members for limiting the distance of further telescoping movement between them in said other direction, and means securing the second member to the sliding closure.
 10. The combination called for in claim 9 in which said securing means is releasable and comprises interlocking elements, one having an opening and the other having an angular member received through said opening and the inner portion of said angular member being disposed in interference engagement with said other interlocking element as oriented by telescopic movement of said second member, said angular member being moved from said interference engagement when said telescoping relationship is disassociated and said telescoping members are moved from axial alignment.
 11. The combination called for in claim 9 in which said securing means comprises hook-and-eye elements and the terminal end of said hook is disposed at an angle to the axis of the telescoping relation. 